You can't assign a voltage to a current source. You can only say the current in a loop is equal to the current sources in that loop. Or at least I thought....... doing that is not working for problem 10 and 11.

Since when using the loop method, what you do is add all the VOLTAGES around the loop, you must select a voltage to be across the current source, but it can be an unknown. I selected the symbol Vc to represent the voltage across the current source, with + at the top. Then the loop equations can be written:

Take the first two elements of the solution vector and set up the equation:

(Vc - 30)/2 + (Vc - 40)/4 = 2

because we do know that i1 + i2 = 2. That is, the 2 amps out of the current source has to equal the sum of i1 and i2. Solve this equation and get Vc = 36. Substitute 36 for Vc in the solution vector and get i1 = 3, i2 = -1 and i3 = .5 Problem solved.

hi jut,
i think where u went wrong was u took i=2A in loops which had the 2A source in common,
the 2A is the current flowing thru the current source(like current flowing thru an element) it is different from the loop current.
the current thru the 2 A current source should be 2A=i1 + i2 ----for 10
and 2A=i1 + i3. -------for 11.
it think the method posted in the above post is a good one.

Connect with Us

Sign Up

Quote of the day

“Electrical science has disclosed to us the more intimate relation existing between widely different forces and phenomena and has thus led us to a more complete comprehension of Nature and its many manifestations to our senses.”